Keybase Chat - End-to-end encrypted chat built into Keybase
Spike - Spike solves businesses' communication chaos by bringing together email, team chat, collaborative docs, and meetings, into one feed.
Hermes - Pandora Client for OS X
Crypho - End-to-end-encrypted messaging and file sharing
Cyph - Cyph is the name of a completely free chatting website that provides its visitors with a secure and safe chatting environment.
dPhone - The most secure calling app. Open Source and Free.